1. Field of the Invention
This invention pertains generally to the field of safety devices for electrical power tools and, more specifically, to a device for regulating the flow of electrical current to a power tool.
2. Description of the Background Art
The use of power tools has significantly increased the level of efficiency with regard to the time and amount of labor required to build a variety of products. However, the benefits provided by power tools has not been without costs, as numerous industrial accidents resulting from power tools are reported each year. As a result, a number of safety devices have been created to help avoid accidents relating to the use of power tools.
One safety solution has been to create devices which regulate the flow of electrical current to a power tool, by either diminishing the amount of current, thus slowing the tool, or else stopping the flow of current, thereby stopping the tool, completely. In this manner, should the power tool become stuck in a work piece, or else present some other danger, the electrical power can be readily slowed, or cut off, thereby diminishing the danger presented by the tool. A typical example of this type of solution is seen in the spring-activated cut-off switches, which are built into most hand held power tools, such as hand drills and radial saws. The cut off switches built into these tools, efficiently cut power to these tools, should there be a need to do so.
In large, stationary, industrial power tools, such as lathes and drill presses, a variety of power cut off devices have also been devised. U.S. Pat. No. 2,357,690, issued to J. P. Rugheimer, discloses a drill press equipped with a power cut off switch which toggles between an "on" and an "off" position, upon being bumped by the drill press sleeve. U.S. Pat. No. 1,589,977, issued to A. Lucas, discloses a spring-activated cut off switch for a welding machine. U.S. Pat. No. 4,135,068, issued to Burns, discloses a cut off switch assembly for a sand blaster, which can be coupled to the sand blaster by a pair of clamps.
Many industrial power tools are manufactured with switches of a "toggle" variety, as mentioned previously, in the Rugheimer patent, which must be manually switched between an "on" and an "off" position. Moreover, many of these toggle switches are not positioned for easy access, should it become immediately necessary to cut the power to a tool. U.S. Pat. No. 4,530,624, issued to Cuneo, proposes a solution to this access problem by locating a power switch on the end of a drill press handle. However, the device disclosed in Cuneo is of a built-in variety and therefore cannot be used to adapt to an existing industrial tool lacking a power regulating switch.
A need therefore exists for a device which can convert an existing industrial tool lacking a power regulating switch, into a safer tool which incorporates such a switch. The present invention satisfies this need, as well as overcomes the deficiencies of the devices heretofore developed.
The foregoing discussion and patents mentioned herein, reflect the state of the art of which the applicant is aware and are tendered with the view toward discharging applicant's acknowledged duty of candor in disclosing information which may be pertinent to the examination of this application. It is respectfully stipulated, however, that none of these patents teach or render obvious, singly or when considered in combination, applicant's claimed invention.